1. Field of the Invention
The invention relates to a sheet feeder with electrostatic dust-collecting function, and more particularly to a sheet feeder for attracting dust according to electrostatic charges generated by an electrostatic charge generator so as to remove the dust. The sheet feeder of the invention is suitable for various document processing devices, such as a scanner, a copier, a printer, a multi-function peripheral, and the like.
2. Description of the Related Art
Most of the conventional automatic document feeders, especially the automatic document feeders for scanners, do not have the dust-removing design. Although some feeders have the dust-collecting designs, the dust including paper flakes and particles is usually collected in a dust-collecting box. However, if the rotational speed of the roller increases, the dust collected in the dust-collecting box tend to be rolled up by an air stream and then go back to a paper path, such that the scan quality or the print quality is influenced. Such a condition tends to be easily caused as the sheet feeding speed is getting higher and higher. Alternatively, the paper flakes and particles in the dust-collecting box tend to go back to the paper path as the automatic document feeder is transported, and the scan or print quality is thus influenced.
Taiwan patent publication No. 563627 discloses a dust-removing device for a sheet feeder, in which the paper flakes or particles on the sheet are blown and sucked away using a blowing and sucking mechanism. Usually, the blowing and sucking mechanism cannot completely remove the paper flakes and the particles from the sheet, and the paper flakes and particles tend to attach to the roller after the sheet contacts the roller. So, this technology cannot remove the paper flakes or particles from the roller, and the paper flakes or particles tend to influence the processing quality. In addition, this technology needs a huge blowing and sucking mechanism and an air-filtering device. So, this prior art is not suitable for the miniaturized automatic document feeder.
U.S. Pat. No. 6,708,009 discloses a printing device capable of removing dust. The printing device includes a dust-collecting box for collecting the dust and a sponge for scratching the paper flakes and particles from the roller. However, the paper flakes and particles are separated from the paper path due to the gravity. The size of the dust-collecting box has to be increased if it is desired to prevent the paper flakes and the particles from being blown back to the paper path due to the air stream caused by the roller rotating at the high speed. Thus, it is disadvantageous to the development of the miniaturized scanning device or printing device.